// Problem: 
// Contest: 
// URL: 
// Memory Limit: 
// Time Limit: 
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#include<bits/stdc++.h>
using namespace std;
#define int long long
inline int read(){
	int s=0,w=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
	return s*w;
}
signed main()
{
	int T=1;
	cin>>T;
	while(T--)
	{
		int n;
		cin>>n;
		int x,mx=0,mn=INT_MAX;
		for(int i=1;i<=n;i++)
		{
			cin>>x;
			if(x>mx)mx=x;
			if(x<mn)mn=x;
		}
		cout<<mx-mn<<endl;
	}
	return 0;
}
